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au:BAPTISTA-NETO, A.

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Microstructure and diametral fracture strength of spark plasma sintered WC-6Co-0.2B and WC-6Co-0.5B ceramic composites from nanosized and metastable WC powders
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Silva, G. S. de Alencar e

; Leal Neto, R. M.

; Filgueira, M.

; Baptista, C. A. R. P.

; Santos, C. dos

; Ramos, A. S.

Cerâmica

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jun 2022, Volume 68 N. 386 Pages 188 - 198

Abstract: En | Text: En | PDF: En

Abstract The present work aimed at evaluating the microstructures and mechanical properties of spark plasma sintered WC-6 wt% Co ceramic composites doped with boron (0.2 and 0.5 wt%). W-50 at% C (W-6.13 wt% C) powders produced under different milling times (20, 60, 180, and 600 min) were used as starting materials and subsequently mixed with Co (6 wt%) and B (0.2 or 0.5 wt%) powders for 5 min. The resultant WC-Co-B powder mixtures were consolidated by spark plasma sintering at 1450 °C for 10 min at 40 MPa under vacuum in order to obtain the samples with 10 mm diameter and 3 mm thickness. The starting powders and the sintered samples were characterized by laser diffraction particle size analysis, X-ray diffraction with Rietveld refinement, relative density, scanning electron microscopy, energy dispersive spectrometry, Vickers hardness test, and diametral compression test. Supersaturated W solid solution (WSS) with a crystallite size of <50 nm was formed in W-50C (at%) powder mixtures. The relative density of the sintered composites increased with the increasing milling time up to 180 min from 79.7%±0.6% to 86.7%±0.5% for WC-6Co-0.2B and from 86.7%±0.6% to 90.9%±0.4% for WC-6Co-0.5B. Furthermore, the WC phase appeared as the matrix in the sintered samples, and W2CoB2 precipitated homogeneously around WC grain boundaries, mainly to those containing 0.5% B. The Vickers hardness values of the sintered WC-6Co-0.2B and WC-6Co-0.5B ranged from 1790±39 to 2158±25 HV and 1858±31 to 2182±28 HV, respectively. The fracture strength (determined by diametral compression test) varied between 144-353 MPa due to the porosity and precipitates in thin-thickness cylinder samples.

https://doi.org/10.1590/0366-69132022683863210

Upconversion 3D Printed Composite with Multifunctional Applications for Tissue Engineering and Photodynamic Therapy
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Nigoghossian, Karina

; Saska, Sybele

; Christovam, Livia M.

; Coelho, Fernanda

; Beatrice, Cesar Augusto G.

; Lucas, Alessandra A.

; Neto, Paulo I.

; Silva, Jorge Vicente L. da

; Tercjak, Agnieszka

; Baptista, Maurício S.

; Catalani, Luiz Henrique

; Scarel-Caminaga, Raquel M.

; Capote, Ticiana S. O.

; Ribeiro, Sidney José L.

Journal of the Brazilian Chemical Society

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apr 2020, Volume 31 N. 4 Pages 638 - 652

Abstract: En | Text: En | PDF: En

Upconversion nanoparticles (UCNPs) are suitable materials for bioapplications due to their ability to emit visible light under near infrared (NIR) excitation, in the biological transparency range. Polycaprolactone(PCL)-based scaffolds are widely used in tissue engineering in combination with inorganic compounds to improve bioactivity and osteoconductive properties. This work proposes a 3D printed composite scaffold with upconversion property aiming at biomedical applications in therapy-stimulated bone repair and photodynamic therapy (PDT). The system combines PCL polymer, UCNPs-apatite and a PDT photosensitizer. Thermal and rheological behaviors of the composite were similar to pure PCL polymer. Mechanical properties were improved by adding UCNPs-apatite. The 3D printable composite presented upconversion property and potential for PDT application, which was demonstrated by singlet oxygen generation under 980 nm excitation. Cytotoxicity, genotoxicity and mutagenicity assays indicated no toxicological effects at low concentrations of rare earth elements. Taken together, a potential multifunctional material is proposed for biomedical applications.

https://doi.org/10.21577/0103-5053.20190228 489 downloads

Where do we aspire to publish? A position paper on scientific communication in biochemistry and molecular biology
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Baptista, M.S.

; Alves, M.J.M.

; Arantes, G.M.

; Armelin, H.A.

; Augusto, O.

; Baldini, R.L.

; Basseres, D.S.

; Bechara, E.J.H.

; Bruni-Cardoso, A.

; Chaimovich, H.

; Colepicolo Neto, P.

; Colli, W.

; Cuccovia, I.M.

; Da-Silva, A.M.

; Di Mascio, P.

; Farah, S.C.

; Ferreira, C.

; Forti, F.L.

; Giordano, R.J.

; Gomes, S.L.

; Gueiros Filho, F.J.

; Hoch, N.C.

; Hotta, C.T.

; Labriola, L.

; Lameu, C.

; Machini, M.T.

; Malnic, B.

; Marana, S.R.

; Medeiros, M.H.G.

; Meotti, F.C.

; Miyamoto, S.

; Oliveira, C.C.

; Souza-Pinto, N.C.

; Reis, E.M.

; Ronsein, G.E.

; Salinas, R.K.

; Schechtman, D.

; Schreier, S.

; Setubal, J.C.

; Sogayar, M.C.

; Souza, G.M.

; Terra, W.R.

; Truzzi, D.R.

; Ulrich, H.

; Verjovski-Almeida, S.

; Winck, F.V.

; Zingales, B.

; Kowaltowski, A.J.

Brazilian Journal of Medical and Biological Research

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2019, Volume 52 N. 9 elocation e8935

Abstract: En | Text: En | PDF: En

The scientific publication landscape is changing quickly, with an enormous increase in options and models. Articles can be published in a complex variety of journals that differ in their presentation format (online-only or in-print), editorial organizations that maintain them (commercial and/or society-based), editorial handling (academic or professional editors), editorial board composition (academic or professional), payment options to cover editorial costs (open access or pay-to-read), indexation, visibility, branding, and other aspects. Additionally, online submissions of non-revised versions of manuscripts prior to seeking publication in a peer-reviewed journal (a practice known as pre-printing) are a growing trend in biological sciences. In this changing landscape, researchers in biochemistry and molecular biology must re-think their priorities in terms of scientific output dissemination. The evaluation processes and institutional funding for scientific publications should also be revised accordingly. This article presents the results of discussions within the Department of Biochemistry, University of São Paulo, on this subject.

https://doi.org/10.1590/1414-431x20198935 1769 downloads

Ecological water quality assessment in the Guapiaçu-Macacu hydrographic complex (Rio de Janeiro, Brazil) using multiple indicators
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Pereira, Priscilla S.

; Fernandes, Lia A. C.

; Dias, Roberto J. P.

; Sampaio, Marcelo S.

; Silva-Neto, Inácio D.

; Baptista, Darcilio F.

; Oliveira, Jaime L. M.

Revista Ambiente & Água

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sep 2014, Volume 9 N. 3 Pages 409 - 423

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

O diagnóstico rápido da qualidade da água de cinco pontos do complexo hidrográfico Macacu-Guapiaçu foi realizado utilizando protocolo de avaliação visual (PAV), análises convencionais, composição e estrutura do grupo de ciliados e a ocorrência de macroinvertebrados bentônicos. Foram realizadas coletas de amostras da água em cinco pontos amostrais (A - E) em julho de 2010. Os protistas foram amostrados com auxílio de substratos artificiais e os macroinvertebrados utilizando método multi-habitat. Foram registrados 22 táxons de protozoários e 51 táxons de macroinvertebrados nas cinco amostras. O ponto de referência (A) apresentou maior diversidade de protistas e maiores índices BMWP-CETEC e IBE-IOC em relação aos grupos de macroinvertebrados. Os trechos mais impactados apresentaram menor diversidade e maior abundância de protozoários bem como menores valores para os índices. Os quatro métodos utilizados foram convergentes ao diagnosticar os trechos de referência (A), impactado (B e E) e com grau intermediário de impacto (C e D). Além disso, estes métodos foram complementares visto que os parâmetros convencionais e a composição de ciliados foram mais sensíveis na detecção do aumento da poluição orgânica enquanto que o PAV e a ocorrência de macroinvertebrados detectaram alterações na geomorfologia e degradação do habitat.

A quick diagnosis of the ecological quality of five sections of the Macacu-Guapiaçu hydrographic complex was performed using visual assessment protocol (VAP), conventional analysis, composition and structure of ciliates and the occurrence of benthic macro invertebrates. Water samples were collected from five sampling stations (A-E) in July of 2010. Protists were sampled with aid of artificial substrates, and macro invertebrates were sampled using the multi-habitat method. A total of 22 taxa of protozoa and 51 taxa of macro invertebrates was registered at the five stations. Reference station (A) showed greater protist diversity and higher values of BMWP-CETEC and IBE-IOC indices relating to macro invertebrates. The impacted stations (B and E) presented lower diversity and higher abundance of protozoa, as well as the lowest values for the rates. The four methods used were convergent to diagnose reference station (A), the impacted stations (B and E) and those in intermediate conditions (C and D). Thus, the methods were complementary, as the conventional parameters and ciliate assembly were more sensitive to detecting the increase in organic pollution and VAP and macro invertebrate assembly detected changes in geomorphology and habitat degradation.

https://doi.org/10.4136/ambi-agua.1397 1820 downloads

The Role of the Humic Substances in the Fractioning of Heavy Metals in Rodrigo de Freitas Lagoon, Rio de Janeiro - Brazil
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FONSECA, ESTEFAN M. DA

; BAPTISTA NETO, JOSÉ A.

; MCALISTER, JOHN

; SMITH, BERNARD

; FERNANDEZ, MARCOS A.

; BALIEIRO, FABIANO C.

Anais da Academia Brasileira de Ciências

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2013, Volume 85 N. 4 Pages 1289 - 1301

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Um dos principais resultados dos processos relativos da urbanização é a contaminação de corpos d'água adjacentes. Inserida neste contexto, a Lagoa Rodrigo de Freitas está situada na zona sul da cidade do Rio de Janeiro. Este ecossistema recebe uma série de descargas contendo todos os tipos de poluentes incluindo metais pesados. O presente trabalho estudou o fracionamento dos metais pesados nos sedimentos da Lagoa Rodrigo de Freitas assim como identificou a influência da matéria orgânica na dinâmica de partição. Os resultados das análises indicaram a matéria orgânica como um importante agente ligante. Características peculiares como sedimentos redutores, altas concentrações de metais pesados e granulometria fina transformaram este ecossistema em um depósito efetivo de metais pesados, onde os mesmos não se apresentam em frações facilmente remobilizáveis.

One of the main results of the processes related to urbanization is the contamination of the adjacent water bodies. Inserted in this context, the Rodrigo de Freitas lagoon is situated in the south zone of the city of Rio de Janeiro. This ecosystem receives several inputs containing all sorts of pollutants, including heavy metals. The present work aimed to study the partitioning of heavy metals in the sediments of Rodrigo de Freitas and the influence of organic matter in this fractionation dynamic. The results of these analyses presented the contents of organic matter as an important metal-capturing agent. Fractionation of organic matter resulted in a predominance of humine. Heavy metal partitioning showed that the metals bound by the water-soluble phase have no significant concentrations. Special features such as, reducing sediment, high levels of organic matter and fine grain size have transformed this ecosystem in an effective deposit of pollutants, where heavy metals are not available in easily reactive fractions.

https://doi.org/10.1590/0001-3765201371011 3630 downloads

Geochronology and heavy metal flux to Guanabara bay, Rio de Janeiro state: a preliminary study
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Baptista Neto, José A.

; Peixoto, Tomás C.S.

; Smith, Bernard J.

; Mcalister, John J.

; Patchineelam, Soraya M.

; Patchineelam, Sambasiva R.

; Fonseca, Estefan M.

Anais da Academia Brasileira de Ciências

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2013, Volume 85 N. 4 Pages 1317 - 1327

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

A Baía de Guanabara, localizada no estado do Rio de Janeiro, é cercada pela segunda mais importante área metropolitana do país. Nas últimas décadas, a urbanização e outros processos na área circundante têm aumentado significativamente a entrada de sedimentos para a baía, tendo um efeito negativo sobre todo o meio ambiente. Estes impactos negativos estão relacionados com grandes volumes de esgoto sem tratamento e efluentes industriais. O presente estudo avalia a história deste impacto humano através do exame detalhado de um testemunho coletado na porção norte da Baía de Guanabara. A geocronologia é estabelecida usando 210Pb e relacionada com o carbono orgânico e fluxos de metais pesados para os sedimentos. Os resultados indicaram uma taxa de sedimentação média de 0,67 cm.y-1. O fluxo de carbono orgânico e metais pesados começaram a aumentar no início do século passado e os maiores valores foram observados no topo do testemunho.

Guanabara Bay, located in Rio de Janeiro state. It is surrounded by the second most important metropolitan area of the country. Over recent decades, land disturbance and urbanization in the surrounding area has significantly increased sediment input to the bay and had a negative effect on its overall environmental. This is especially related to high volumes of untreated sewage and industrial effluents. This study evaluates the history of this human impact through detailed examination of a sediment core taken from the northern portion of Guanabara Bay. A geochronology is established using 210Pb dating and related to organic carbon and heavy metal fluxes to the sediments. This gave a calculated net average sedimentation rate for the core of 0.67 cm.year-1. The organic carbon and heavy metals flux started to increase at the beginning of the last century and the highest values was observed in the top of the cores.

https://doi.org/10.1590/0001-3765201394612 3208 downloads

Spatial distribution of pollen grains and spores in surface sediments of Guanabara Bay, Rio de Janeiro, Brazil
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Barreto, Cintia F.

; Vilela, Claudia G.

; Baptista-Neto, José A.

; Barth, Ortrud M.

Anais da Academia Brasileira de Ciências

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sep 2012, Volume 84 N. 3 Pages 627 - 644

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Com objetivo de investigar a deposição dos grãos de pólen e esporos na Baía de Guanabara, Estado do Rio de Janeiro, 61 amostras de sedimentos superficiais foram analisadas. Os resultados mostraram que a deposição atual dos palinomorfos nos sedimentos superficiais da Baía de Guanabara representa a vegetação regional de sua bacia hidrográfica. A distribuição diferencial dos palinomorfos seguiu um padrão influenciado pela batimetria, velocidade das corretes de marés, descarga dos numerosos rios e pela atividade humana. A dominância dos taxa representantes da Vegetação Campestre reflete as mudanças da flora original causadas por intensas atividades humanas na região. A presença contínua e a grande riqueza de tipos polínicos da Floresta Ombrófila nas amostras, indica que a área fonte pode ser a vegetação das bordas dos rios do setor oeste da Baía, onde a vegetação de mangue está sendo preservada. A grande quantidade de palinomorfos danificados pode estar relacionada ao desgaste que ocorre durante o transporte fluvial, indicando remoção ou retrabalhamento de suas áreas de origem.

Aiming to investigate the deposition of pollen grains and spores in Guanabara Bay, Rio de Janeiro State, 61 surface sediment samples were analyzed. The results showed that the current deposition of palynomorphs in surface sediments of Guanabara Bay represents the regional vegetation of this hydrographic basin. The differential distribution of palynomorphs followed a pattern influenced by bathymetry, tidal currents speed, discharge of numerous rivers, and by human activity. The dominance of representatives of Field Vegetation reflects the changes of the original flora caused by intense human activities in the region. The continued presence and richness of pollen types of rain forest in the samples indicates that their source area might be the vegetation from riparian border of rivers in the western sector of the Bay, where the mangrove vegetation is being preserved. The large amount of damaged palynomorphs may be related to abrasion that occurs during river transport, indicating removal or reworking from their areas of origin.

31641 downloads

Study of heavy metal concentration and partitioning in the Estrela River: implications for the pollution in Guanabara Bay - SE Brazil
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Rangel, Carlos M. A.

; Baptista Neto, José A.

; Fonseca, Estefan M.

; McAlister, John

; Smith, Bernard J.

Anais da Academia Brasileira de Ciências

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sep 2011, Volume 83 N. 3 Pages 801 - 816

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Neste estudo, analises geoquímicas de dez amostras de sedimentos coletadas ao longo do sistema fluvial do rio Estrela, que deságua na porção norte da Baía de Guanabara, evidenciam a presença de impactos antropogênicos nesta área. As concentrações de Fe, Mn, Zn, Cu, Pb, Cr e Ni obtidas foram ligeiramente elevadas, quando comparados com valores encontrados em ambientes naturais. A granulometria e o teor de matéria orgânica na maioria dos pontos analisados mostraram características não favoráveis à acumulação destes poluentes devido à baixa concentração de matéria orgânica e à forte presença de fração areia. Realizou-se também o fracionamento dos metais pesados nos sedimentos e constatou-se a preeminência da fase residual e redutível, além da ocorrência significativa da fração orgânica em alguns pontos analisados. Estes fatores evidenciam, portanto, riscos potenciais de contaminação, onde os metais associados à fase orgânica podem se tornar biodisponíveis em processos de solubilização, proporcionados por mudanças físico-químicas que podem ocorrer neste ambiente aquático.

In this study, the geochemical analysis of ten sediment samples collected along the fluvial system of the Estrela River, which flows into the northern portion of Guanabara Bay, shows the presence of anthropogenic impacts in this area. Concentrations of Fe, Mn, Zn, Cu, Pb, Cr and Ni obtained were slightly higher, when compared with values found innatural environments. The particle size and organic matter content in most of the analyzed stations showed featuresnot conducive to the accumulation of pollutants due to the low organic matter content and the strong presence ofsand fraction. There was also the fractionation of heavy metals in sediments and it was found the prominence ofresidual and reducible phase, besides the significant occurrence of organic fractions in some analyzed stations. Thesefactors, thus, highlight the potential risks of contamination, where the metals associated with the organic phase canbecome bioavailable in processes of dissolution, provided by physico-chemical changes that can occur in this aquaticenvironment.

5218 downloads

Influence of glycerol and ornithine feeding on clavulanic acid production by Streptomyces clavuligerus
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Teodoro, J. C.

; Baptista-Neto, A.

; Araujo, M. L. G. C.

; Hokka, C. O.

; Badino, A. C.

Brazilian Journal of Chemical Engineering

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dec 2010, Volume 27 N. 4 Pages 499 - 506

Abstract: En | Text: En | PDF: En

The influence of glycerol and ornithine feeding on clavulanic acid (CA) production by Streptomyces clavuligerus was investigated. In batch experiments, CA maximum concentration (Cp max) ranged randomly from 430 to 560 mg.L-1, with a maximum increase of 10% in relation to the control run, without ornithine. However, the maximum volumetric productivity of CA (Pp max) of 13.7 mg.L-1.h-1 was obtained with 0.66 g.L-1 of ornithine, 44.2% higher than the Pp max in the control run. In fed-batch experiments, Cp max varied within the narrow range from 1.254 to 1.405 g.L-1, 2.5 times higher than that obtained in the control run. The presence of ornithine increased the Pp max, although it influenced only slightly the Cp max. Concerning glycerol, the highest CA production of 1.6 g.L-1 was obtained in the fed-batch with glycerol and ornithine (180 and 3.7 g.L−1) in a 10-L bioreactor, showing a positive effect of ornithine and glycerol, in the proper proportion (48.6:1), on CA biosynthesis.

2204 downloads Cited 4 times in SciELO

10.

The contribution of heavy metal pollution derived from highway runoff to Guanabara Bay sediments: Rio de Janeiro / Brazil
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Pereira, Edisio

; Baptista-Neto, José A.

; Smith, Bernard J.

; Mcallister, John J.

Anais da Academia Brasileira de Ciências

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dec 2007, Volume 79 N. 4 Pages 739 - 750

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Neste estudo, análises geoquímica e de granulometria de trinta e quatro amostras de sedimentos coletados ao longo de rodovias em um ambiente urbano ao redor da Baía de Guanabara, mostram que o escoamento superficial das rodovias pode ser fonte potencial de metais pesados para a poluição de depósitos sedimentares costeiros. Concentrações de Fe, Mn, Zn, Cu, Pb, Cr e Ni são bem altas quando comparadas com os valores encontrados em ambientes naturais, onde o Fator de Enriquecimento (FE), que é índice de normalização, foi utilizado para a distinção entre fontes naturais e antropogênicas de metais pesados. As análises granulométricas mostram que estes sedimentos são compostos predominantemente de areia e nenhum padrão de distribuição foi observado entre as frações areia, silte e argila. Os altos níveis de matéria orgânica e metais pesados indicam que estes materiais depositados sobre as rodovias são fontes potenciais de poluição para os sedimentos costeiros da Baía de Guanabara.

In this study, geochemical and particle size analyses of thirty-four street sediment samples collected from an urban environment around Guanabara Bay, shows highway run-off to be a potential source of heavy metals for the pollution of near-shore sedimentary deposits. Concentrations of Fe, Mn, Zn, Cu, Pb, Cr and Ni were found to be higher in these sediments when compared to concentrations found in samples from the natural environment, where an Enrichment Factor (EF) index was used to distinguish between natural and anthropogenic sources. Particle size analysis shows these sediments to be predominantly composed of sand and no distribution pattern was observed between the sand, silt and clay fractions. High levels of organic matter and heavy metals would indicate that these street run-off materials are a potential source of pollution for the near-shore sediments of Guanabara Bay.

7986 downloads Cited 3 times in SciELO

11.

Palynological analysis of a sediment core obtained in Guanabara Bay, Rio de Janeiro, Brazil
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Barreto, Cintia F.

; Luz, Cynthia F.P. da

; Baptista-Neto, José A.

; Vilela, Claudia G.

; Barth, Ortrud M.

Anais da Academia Brasileira de Ciências

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jun 2007, Volume 79 N. 2 Pages 223 - 234

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Sedimentos de um testemunho de sondagem coletado a 2 km ao norte da Ilha de Paquetá, Baía de Guanabara foram submetidos à análise palinológica, com o objetivo de reconhecer e interpretar a dinâmica temporal da vegetação na região e a influência antrópica. A datação radiocarbônica realizada próxima à base do testemunho indicou uma idade de 4.210 ± 40 anos AP (idade calibrada). Os resultados possibilitaram determinar quatro zonas palinológicas. Na Zona I, a mais basal, observou-se o decréscimo da concentração total de palinomorfos em direção ao topo e elevada deposição de grãos de pólen e esporos degradados, com o predomínio de grãos de pólen concernentes à floresta ombrófila. Esse resultado pode indicar que nesta zona existia a Mata Atlântica exuberante, sob o domíniode um evento marinho regressivo. Na Zona II, ocorreu um aumento na concentração total de palinomorfos bem preservados, com o predomínio também da vegetação de floresta ombrófila e um aumento expressivo de higrófitas, indicando condições ambientais mais úmidas. Na Zona III, ocorreu uma diminuição nas concentrações dos palinomorfos em direção ao topo, com o predomínio da vegetação campestre. Na Zona IV, localizada próximo ao topo do testemunho, ocorreu uma queda acentuada nas concentrações de pólen e esporos com o predomínio da vegetação campestre e o aparecimento de pólen exótico, evidenciando a influência antrópica no entorno da Baía de Guanabara.

The sediment of a core collected about 2 km north of Paquetá Island, Guanabara Bay, was submitted to pollen analysis, in order to recognize the dynamics of the regional vegetation, and the anthropic influence. Radiocarbon dating of a sample next to the bottom of the core indicates an age of 4.210 ± 40 14C yrs B.P (calibrated age). It was possible to establish four palynological zones. Starting at the bottom of the core, a decrease in palynomorph concentration, the presence of degraded pollen grains and spores, and the predominance of ombrophilous forest pollen grains were observed in the basal portion of Zone I. These data may indicate the presence of an exuberant Atlantic Forest, dominated by a marine regressive event. The concentration of well-preserved palynomorphs increased in Zone II, with the predominance of the ombrophilous forest vegetation also, and an expressive increase of hygrophytes, indicating more humid environmental conditions. Palynomorph concentration decreased again toward the top of Zone III, and the field vegetation was predominant. In the upper Zone IV occurred a strong decrease in pollen and spore concentration, with predominance of field vegetation also, and the appearance of exotic pollen grains, showing the anthropic influence at this time.

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12.

Surface modification of a granite building stone in central Rio de Janeiro
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Baptista-Neto, José A.

; Smith, Bernard J.

; McAllister, John J.

; Silva, Maria Augusta M.

; Castanheira, Fabio S.

Anais da Academia Brasileira de Ciências

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jun 2006, Volume 78 N. 2 Pages 317 - 330

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Com o objetivo de se avaliar os controles ambientais na formação de crostas e deterioração de rochas ornamentais em fachadas de prédios históricos, uma série de mapeamentos e análises fisicas e químicas foram realizados em granitos da fachada de uma igreja histórica numa área poluída no centro da cidade do Rio de Janeiro. Estas técnicas destacam a ameaça crescente dos danos causados pela desagregação granular e esfoliação da rocha que é fortemente percebido por se tratar de um material de alta durabilidade usado na fachada do prédio em áreaslocalizadas ao nível do chão. O exercício de mapeamento possibilitou a demarcação e observação das áreas afetadas pela formação de crosta negra sobre toda a fachada do prédio, principalmente concentradas em áreas abrigadas da ação da chuva. As análises demonstraram a influência de aerosóis marinhos, composição das rochas e argamassas e dos poluentes atmosféricos na deterioração e formação de crostas no granito. Muito da deterioração é associado especificamente a presença de sais, tais como halita (NaCl) e gipsita (CaS0(4).2H2O). O fato da crosta negra de gipsita ser capaz de se desenvolver sobre toda a fachada do prédio, em um ambiente sub-tropical úmido é testemunha da eficácia dos altos níveis de poluição local, especialmente da deposição de particulados, e da reduzida lavagem pela chuva em um micro-ambiente protegido,em ruas estreitas, que funcionam como corredores de poluição, impedindo a tendência da gipsita ser lavada das fachadas dos prédios históricos. Essa observação destaca que os processos de intemperismo operante, são principalmente controlados por condições microclimáticas.

In order to evaluate environmental controls on the soiling formation and decay of building stones a set of mapping and physical and chemical analyses were carried out on granite from a historical church in the polluted centre of Rio de Janeiro. These techniques highlight the increasing of threatening damage on generally perceived as a durable building material, caused by granular disaggregation and contour scaling in areas close to ground level. Mapping also indicated the formation of black crusts over entire building façades, concentrated on areas sheltered from rain-wash. Analyses demonstrated the influence of marine aerosols, rock and mortar composition and mostly of the atmospheric pollutants on the decay and soiling of the granite. Much of the decay is associated specifically with the presence of halite (NaCl) and gypsum (CaS04.2H2O). The fact that black, gypsum crusts are able to develop over entire façades in a humid subtropical environment is testimony to the high levels of local pollution, especially particulate deposition. Reduced rainwash, in sheltered micro-environments of narrow, canyon-like streets, overcomes the gypsum tendency to bewashed away from buildings façades. These observations further highlight that decay processes are primarily controlled by microclimatic conditions.

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13.

Studies on the rheology and oxygen mass transfer in the clavulanic acid production by Streptomyces clavuligerus
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Gouveia, E. R.

; Baptista-Neto, A.

; Hokka, C.O.

; Badino Jr., A.C.

Brazilian Journal of Chemical Engineering

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dec 2000, Volume 17 N. 4-7 Pages 827 - 834

Abstract: En | Text: En | PDF: En

In the present work rheological characteristics and volumetric oxygen transfer coefficient (kLa) were investigated during batch cultivations of Streptomyces clavuligerus NRRL 3585 for production of clavulanic acid. The experimental rheological data could be adequately described in terms of the power law model and logistic equation. Significant changes in the rheological parameters consistency index (K) and flow behavior index (n) were observed with the fermentation evolution. Interesting correlations between the consistency index (K)/biomass concentration (C X) and the flow behavior index (n)/biomass concentration were proposed. Volumetric oxygen mass transfer coefficient (kLa) was determined by the gas balance method. Classical correlation relating the volumetric oxygen mass transfer coefficient to the operating conditions, physical and to transport properties, including apparent viscosity (muap), could be applied to the experimental results.

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14.

Phenomenological model of the clavulanic acid production process utilizing Streptomyces clavuligerus
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Baptista-Neto, A.

; Gouveia, E.R.

; Badino-Jr, A.C.

; Hokka, C.O.

Brazilian Journal of Chemical Engineering

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dec 2000, Volume 17 N. 4-7 Pages 809 - 818

Abstract: En | Text: En | PDF: En

The kinetics of clavulanic acid production process by Streptomyces clavuligerus NRRL 3585 was studied. Experiments were carried out in a 4 liters bioreactor, utilizing 2 complex media containing glycerol as the carbon and energy source, and peptone or Samprosoy 90NB (soybean protein) as nitrogen source. Temperature was kept at 28°C and the dissolved oxygen was controlled automatically at 40 % saturation value. Samples were withdrawn for determination of cell mass (only peptone medium), glycerol and product concentrations. Gas analyzers allowed on line determination of CO2 and O2 contents in the exit gas. With Samprosoy, cell mass was evaluated by determining glycerol consumption and considering the cell yield, Y X/S, as being the same for both cases. Oxygen uptake and CO2 production rates were strongly related to growth and substrate consumption, allowing determination of stoichiometric constants in relation to growth, substrate, oxygen, product and carbon dioxide.

3614 downloads Cited 4 times in SciELO

15.

Caracterização da ocorrência de padrões de sonar de varredura lateral e sísmica de alta freqüência (3,5 e 7,0 kHz) na porção sul da Baía de Guanabara - RJ
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Quaresma, V. S.

; Dias, G. T. M.

; Baptista Neto, J. A.

Revista Brasileira de Geofísica

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aug 2000, Volume 18 N. 2 Pages 201 - 214

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

A correlação de dados geofísicos (sonar de varredura lateral e perfilador de subfundo - 3,5 e 7,0 kHz) permitiu a caracterização da distribuição de sedimentos de fundo na porção sul da Baía de Guanabara. Foram reconhecidos quatro tipos de ecocaráteres: o tipo 1, onde não ocorre penetração do sinal acústico e está relacionado a um fundo arenoso e a um padrão de reflexão do sonar homogêneo cinza claro com sand wave e mega-ripples; o tipo 2A, onde é observada a penetração do sinal com refletores do embasamento acústico e um fundo predominantemente lamoso com alto teor de areia fina a muito fina e padrão homogêneo cinza claro de sonar; o tipo 2B, com penetração do sinal com refletores sendo observados junto a um fundo predominantemente arenoso, com alto teor de lama e padrões de sonar homogêneos cinza escuros; e o último ecocaráter observado, o tipo 3, com penetração do sinal com uma série de refletores múltiplos, observando-se um fundo lamoso com alto teor de areia fina a muito fina e reflexão homogênea cinza escuro nos sonogramas.

The correlation of geophysical data (side-scan sonar and subbottom profiler - 3.5 and 7.0 kHz) has enabled the characterization of the sediment distribution along the southern portion of the Guanabara Bay (Rio de Janeiro - Brazil). Four distinct echocharacter types were recognized: type 1 shows no penetration of the acoustic signal, it is associated with a sandy bottom and with a light gray homogeneous sonograph pattern with sand waves and mega ripples; type 2A presents internal reflectors and the acoustic basement, it is related to a muddy bottom with high content (%) of fine sand and to light gray homogeneous sonograms; type 2B is marked by signal penetration and is related to a sandy bottom with high content (%) of mud and to dark grey homogeneous sonograms; and, finally, type 3 with signal penetration and multiples, it is associated with a muddy bottom with high content (%) of fine sand, and is related to dark gray homogeneous sonograph patterns.

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